Phase I research is aimed at developing a rapid and sensitive assay to detect cells infected with the Epstein-Barr virus (EBV) by combining microencapsulation technology, fluorescence in situ hybridization (FISH), tyramide signal amplification, and flow cytometry. EBV is the causal agent of most cases of infectious mononucleosis. To date, EBV nucleic acids have been identified in endemic Burkitt's lymphoma, AIDS, transplantation-related lymphoproliferative disorders, Hodgkins disease, certain T- and B-cell high grade lymphomas, and nasopharyngeal carcinoma.. Although widely used in research, the polymerase chain reaction assay is not an ideal diagnostic test due to the huh rate of false positive results. Determination of the number of EBV-infected cells and their state of replication or latency is also not possible. Such information would be useful for predicting and monitoring therapeutic efficacy. Our proposed assay will permit detection of rarely occurring EBV-infected cells both in their latent and replicative phases. Rare cell detection is possible due to cell recovery rates of over 90% compared with recovery rates of 20-50% using conventional methods. PROPOSED COMMERCIAL APPLICATIONS: The proposed assay permits early and rapid detection of the status of EBV in infected cells, and monitoring of therapeutic efficacy. Clinical diagnostics represents a $ 1.0 billion market by the year 2000.